Occupational safety and health, including crane signals and exclusion zones
Occupational safety and health, including crane signals and exclusion zones
This domain tests the safety system around the lift: who signals, who is excluded, and what stops the job.
Signals and communication
- One designated signalman, identifiable by vest or gloves, with a clear view of the load and the operator. Anyone may give the emergency stop signal and the operator must obey it.
- Signals are agreed at the pre-lift briefing. If signals are ambiguous or the distance is too great, switch to radio on a dedicated channel with a hand-signal fallback. An unclear signal is a stop signal.
- Standard signals include hoist and lower (forefinger circling), boom up/down, swing left/right, travel, dog everything (clenched fists), stop (one hand), emergency stop (both hands).
Exclusion zones
- Barricade the full swing radius measured from the centre of rotation, covering the largest of load radius plus load dimension, tail swing, and lagging sweep, plus a buffer.
- Nobody under a suspended load; no hands on the load to steady it - use tag lines from outside the fall zone.
- Maintain crane-to-crane and crane-to-structure clearance and control access with barriers and a banksman.
- Weather, lighting and heat are part of the zone: state wind limits, lightning stop criteria, and lighting for night work.
Worked example
A crane with 4.5 m tail swing working at 12 m radius. The controlling dimension is the 12 m load radius plus the carried load dimension, not the smaller 4.5 m tail swing; barricade that larger envelope plus a buffer, and keep the signalman outside it with a clear line of sight.
Traps
Letting an unbriefed rigger signal; standing inside the swing radius to "guide" the load; assuming only the signalman can call stop; forgetting counterweight tail swing when the boom is short.